With use, the edge of a knife blade becomes deformed and the knife loses its cutting ability. How long it takes before a knife starts to lose its edge depends on several factors, such as the hardness of the blade, but one important influence is the surface you are cutting against. You should always use a proper chopping board of wood or plastic. Don't use a glass or marble surface, as this will blunt your knife quickly and may even damage it.

If you spend money on quality knives, you should keep them sharp! The effectiveness of a sharpening tool depends on its hardness and on the coarseness of its surface. In general, you should use a tool made of a material harder than your knife blade, which is why we recommend ceramic or diamond tools, as both of these materials are harder than knife steel. Just as chopping against a hard surface will deform your knife's edge more quickly, a hard surface will make the sharpening process quicker and easier. The coarseness of the sharpener's surface determines how much metal is removed from the blade. This coarseness is expressed as a number, with lower numbers showing increasing coarseness. 500 grade or below would normally be regarded as coarse, medium grade is typically 1000, and a grade of 3000 and up is fine grade. A coarse diamond tool will quickly remove a significant amount of steel from your blade (and so is dangerous if you don't know what you are doing!), while at the other extreme a leather barber's strop will simply clean and condition a blade edge that is already razor sharp.

In general, sharpening a kitchen knife should involve removing very little metal from the blade, unless you are creating a new edge on a very blunt or damaged knife. The sharpening process is more about re-aligning the edge of the blade. The sharpening tools we sell are medium grade ceramic, which we think represents the best compromise for most cooks. A whetstone gives you most control over the sharpening process, and so will give you the best results if you are prepared to invest a little time in learning how to use it. The ceramic disc sharpeners we sell will not give you such a fine edge, but are very quick and easy to use, and will give an edge that will satisfy the majority of cooks.

Store your knives in a proper knife block, either the standard counter-top type or an in-drawer model. We do not recommend using magnetic strips for storing thin-bladed Japanese knives. If the strip is strong enough to hold the knives safely, pulling a knife off it will exert a strong lateral force on the blade, and in extreme cases may even snap it.

After use, rinse your knives in soapy water and dry them before putting them away. Never put quality knives in a dishwasher. Even if they have metal handles, the buffeting they receive can damage the blades, and poking around in a dishwasher for sharp knives is not to be recommended (for the same reason, never leave sharp knives at the bottom of a dishwashing bowl).

It is not necessesary to oil the blades of most modern Japanese kitchen knives. Oiling a blade seals and protects it from tarnishing, but most knife steel now incorporates alloys that make it very tarnish-resistant. Of the knife ranges we sell, only the Hamada range, which has blades of traditional pure high-carbon steel, will tarnish easily. If you do wish to oil your knives, any light edible oil, such as sunflower oil, will do.